Neurological manifestations of SARS-CoV-2 infection: Evidence for Nervous System invasiveness

Manifestazioni neurologiche in corso di infezione da SARS-CoV-2: evidenza di invasivita del Sistema Nervoso Background: SARS-CoV-2 mainly affect the respiratory system; however virus-related neurological manifestations are being reported more and more frequently in the scientific literature. Despite the expanding literature that discusses insights into the clinical picture and the possible mechanisms by which the SARS-CoV-2 virus invades the nervous system, data on the neuropathologic findings of patients who died following SARS-CoV-2 infection is still limited. Thus, the aim of this study is to focus on the currently available neuropathological data on COVID-19 including post-mortem findings of patients who died from COVID-19 infection. Materials and method: A broad literature search was done for published articles that reported on neuropathological findings of the brain in patients with COVID-19 in PubMed which were released prior to December 31, 2020. Duplicate removal was followed by screening of all titles and abstracts. Based on the inclusion criteria full texts, and supplementary files of all the selected articles were comprehensively analyzed. Simple and relative frequency and proportions were used and summarized in tables. Results: Overall, 35 articles and 259 patients were included. Among the pooled data, SARS-CoV-2 RNA and viral proteins were detected in 47.4% (72/152) and 30.6% (26/85) patients, respectively. Brain edema was found to be the most common macroscopic finding and was described in 12.6% (19/151) of patients, followed by hemorrhagic and ischemic lesions with frequencies of 9.3% (14/151) and 8.3% (12/151), respectively. Among the microscopic findings astrogliosis, microgliosis and T cell lymphocytic infiltrates were reported with frequencies of 92.7% (76/82), 72.2% (75/104), 61.7% (79/128), respectively. Conclusions: The neuropathologic changes described may probably represent direct cytopathic effects together with indirect effects secondary to host inflammatory response induced by the viral infection. Further studies however are required, in which the results need to be compared to a control group which may possibly help to better elucidate the underlying pathologic mechanism.